1: Deciding what kind of streamer you want to fish with. There are many kinds, weights, and sizes of streamers. All these factors play a big role in streamer fishing and picking out your equipment for the day. For example: Small light weighted streamers can be fished with a 4 weight fly rod all the way up to a 6 weight. Big heavy streamers you will want to fish a 6 weight fly rod all the way up to an 8 weight rod.
2: Picking out your fly line. Fly lines come in a wide variety: floating, sinking, and lake specific. On sinking lines you will see IPS on the package. This means itches per second. So if you see 7 IPS, this means that fly line will sink at a rate of 7 inches per second. What river are you going to fish with streamers can help you decide what fly line you need. Deep rivers I like 7 to 9 IPS sinking lines, shallow creeks or rivers I like floating line or 1.5 IPS sinking line, and for rivers that have a good combination of both I use 3 IPS or 5 IPS, depending on time of year. Lake streamer fishing is most commonly done with a 1.5 IPS to 3 IPS because you want your bug to spend a good amount of time in each water column.
3: Your leader set up. When streamer fishing your leader is very important. I like a very strong leader for many reasons. You can bring in the fish faster, which is good for the health of the fish. Also, if the fish runs towards structure you have some holding power, and trout don't seem to be leader shy when chasing streamers. I make my own leaders for streamer fishing but a really good substitution to that is to use a 0 to 1x leader. You can also use a 4x leader similar to what is used for nymphing and then cut it at about the 5ft Mark, if it was a 9 foot leader. This is a great way to use your old leaders.
4: Choosing a knot. What knot to tie to the streamer is one of the most underrated aspects of streamer fishing. I suggest the canoe knot. It is a loop knot that let's the fly have the ability to have lots of extra movement.
5: It's time to fish!! My favorite way to streamer fish is to cast the fly directly in front of me towards the other bank. I then let the streamer dead drift with the natural current as it goes down stream. I keep the line just taut enough to feel if I get a grab. If I don't get a grab I continue to let it float until the line gets almost straight. I then strip the fly in with 6 inch strips back towards me. You can strip fast, slow, or medium paced. Keep changing it up until you find what the fish like.
6: How to set the hook. On streamer fishing you will want to use a strip set. A strip set is done by striping the line back towards you with the tip of your rod low towards your fly. When you feel that tug strip again, hard and fast to set that hook. If you didn't get the fish on let the fly sit there for a second before stripping again. Often times the fish will come back again and hit the streamer if it stops because it looks hurt or stunned.
Learning something new can often times be overwhelming and challenging especially when you are new to a sport. The good news is streamer fishing is well worth learning. It is one of the most exhilarating feelings when you get a take on the streamer, some would claim that it is their favorite way to fish for trout!